In a battery system, the output voltage can be increased by connecting a lot of battery cells in series, and the charge/discharge current can be increased by connecting the battery cells in parallel. Therefore, in the battery system for large current, high voltage used in a hybrid car or an electric vehicle, a plurality of battery cells are connected in series to increase the output voltage. Since the battery system used in this type of a use generates heat by charge or discharge with large current, it is necessary to forcibly cool the battery cells. In order to realize this, the battery system is developed which includes a battery stacked block having a plurality of battery cells stacked, and cooling gaps between the battery cells (Japanese Patent Publication No. 2006-286547).
In this battery system, a battery stacked block is made by stacking the plurality of the battery cells such that spacers are held between the battery cells so as to form cooling gaps. A cooling gas such as air is blown to the cooling gaps, and then the battery cells are cooled from their surfaces. Therefore, in this battery system, a lot of the stacked battery cells can be cooled by the cooling gas such as air blown to the cooling gaps.